JPS62229952A - Mis type semiconductor integrated circuit device - Google Patents

Abstract

PURPOSE:To obtain the MIS type semiconductor integrated circuit device provided with a monitoring transistor with which an lmuAVth and an externally inserted Vth can be made to have an equal value by a method wherein the monitoring transistor, on which the ratio of the width and length of a channel is set in such a manner that the voltage (1muAVth) between a gate and a source will be made equal to the threshold voltage (externally inserted Vth), is provided. CONSTITUTION:The drain and source of an MOS transistor Q1 are connected to the drain and source of a P-channel type MOS transistor Q2, and a pad 14 is connected to these gates respectively. The W/L of the N-channel type MOS transistor Q1 is set at 40/4, for example, and the W/L of the above- mentioned P-channel type MOS transistor Q2 is set at 20/4, for example. In other words, the size of said transistors is set corresponding to the ratio of the (gm) of the N-cannel type MOS transistor Q1 and the (gm) of the P-channel. type MOS transistor Q2. As a result, the 1muAVth and the externally inserted Vth are made equal.

Description

[Detailed Description of the Invention] [Object of the Invention] (Industrial Application Field) This invention relates to an MIS (metal-insulator-semiconductor) type semiconductor integrated circuit device, and in particular, to a device for testing threshold voltage. related to the monitor transistor.

(Prior Art) Generally, in an MIS type semiconductor integrated circuit device, 0
Regardless of the MO8 type or the NMO8 type, as shown in FIG. 2, monitor transistors 17, 181 and 182 are provided in at least one of the vacant areas on the same chip 15 or on the scribe line 16 to inspect the manufacturing process. It is always provided. This monitor transistor 17.181
, 182 are mainly used for testing the threshold voltage vth, and are used to ensure that the semiconductor integrated circuit device completed through a predetermined manufacturing process reaches the threshold voltage vth (as intended and set at the time of design). It is used to check whether the The above threshold voltage vth is normally tested as shown in FIG.
When a drain-source current of 1 os flows, the gate
It is determined by the source-to-source voltage Vos.

Such threshold voltage measurement is easily determined using a curve tracer, and is therefore often used in inspecting completed wafers. However, this threshold voltage varies depending on the size of the transistor. In other words, the gate-source voltage Van when the drain-source current Ioa is 1 μA is the threshold voltage vt.
h, if the ratio W/L of the channel width W to the channel length of the MOS transistor is large, vth will be small, and if W/L is small, vth will be large. Of course, even if the W/L is the same, vth changes depending on differences in the manufacturing process (for example, differences in oxide film thickness).

The amount of change in this vth is about 0.5V at maximum.

On the other hand, at the time of design, the threshold voltage (1 μA V th) described above is not used, but an extrapolated vth that does not depend on the W/L of the transistor is used.

As shown in FIG. 4, this extrapolation vth is the drain-source voltage Vos-5V, and the gate-source voltage Vos
The data is extrapolated from the graph of the square root of the drain-source current V I o a, and the Vos at the point intersecting the Vos axis is
is defined as the threshold voltage vth. Regarding the threshold voltage vth in this definition, the difference in W/L of the transistor appears as a difference in the slope of the data of Vos-V]=this 1-, but the extrapolation point is almost the same. Therefore, the threshold voltage vth does not change due to the difference in W/L of the transistor.

As described above, the threshold voltage used by manufacturing process engineers (1 μA V th) and the threshold voltage used by design engineers (extrapolated V th) are becoming more and more important, so the discussion of the V th margin is important. It has the disadvantage of causing confusion when doing so.

(Problems to be Solved by the Invention) As mentioned above, in conventional MIS type semiconductor integrated circuit devices, the threshold voltage (1 μA V th) used by manufacturing process engineers and the threshold voltage used by design engineers The threshold voltage (extrapolated vth) to be used is different, which has the disadvantage of causing confusion when discussing the vth margin.

Therefore, the purpose of this invention is to calculate 1 μA V th and extrapolate v
M equipped with a monitor transistor that can make th the same value
An object of the present invention is to provide an IS type semiconductor integrated circuit device.

[Structure of the invention] (Means for solving the problem and their effects) In other words,
In order to achieve the above object, in this invention, the ratio of the channel width to the channel length is such that when a predetermined voltage is applied between the drain and the source, a current of 1 μA flows between the gate and the source. voltage (1μAVtl
+) and the threshold voltage (extrapolated Vth) extrapolated from the square root of the gate-source voltage and drain-source current when a specified voltage is applied between the drain and source.
A monitor transistor is provided that is set so that the values are equal to each other. , (Example) An example of the present invention will be described below with reference to the drawings. FIG. 1 shows an example of the configuration of a monitor circuit, in which the drain and source of an N-channel MOS transistor Q1 are connected between pads 11 and 12, respectively.
A P-channel type MO is connected between the pad 13 and the pad 12.
The drain and source of the S transistor Q2 are connected to each other. And each of the above MOS transistors Q1, Q
Pads 14 are connected to the gates of 2, respectively. As shown in FIG. 2, this monitor circuit is provided in at least one of the empty area on the chip 15 and the scribe line 16.

The W/L of the N-channel MOS transistor Q1 is, for example, 40/4, and the W/L of the P-channel MOS transistor Q
The W/L of 2 is set to 20/4, for example. In other words,
The size is set to correspond to the ratio of gm of N-channel type MOS transistor Q1 to gm of P-channel type MOS transistor Q2. Such W/L is N
This is because the mobility of a channel type MOS transistor is approximately twice that of a P channel type MOS transistor. As a result, 1 μAVth and extrapolated vth become equal. However, the dimensions of each monitor transistor above (W/L
) needs to be set to an optimal value depending on the manufacturing process, etc.

With this configuration, 1 μAVth, which can be easily measured by manufacturing engineers, can be equalized with the extrapolated vth used by design engineers, so when discussing the product's vth margin, etc., the vth defined by both parties can be equalized. There is no need for conversion and no confusion.

In the above embodiment, the case where the MIS type semiconductor integrated circuit device is 0MO8 type was explained, but in the same way, NM
Of course, it can also be applied to the O8 type.

[Effect of the invention 1 As explained above, according to this invention, 1 μA V t
A MIS type semiconductor integrated circuit device is obtained that includes a monitor transistor that can make h and extrapolated vth the same value.

[Brief explanation of drawings]

FIG. 1 is a diagram for explaining a configuration example of a monitor circuit in a MIS type semiconductor integrated circuit device according to an embodiment of the present invention, FIG. 2 is a diagram for explaining an example of the arrangement of a monitor transistor and a monitor circuit, Figure 3 is 1μ
FIG. 4 is a diagram for explaining the definition of AVth. FIG. 4 is a diagram for explaining the definition of extrapolated vth. 11-14... Pad, Ql, Q2... Monitor transistor, 15... Chip, 16... Scribe line, 17° 1ax, 182... Monitor transistor, monitor circuit. Applicant's agent Patent attorney Takehiko Suzue No. 1 Figure 612rI! J

Claims (2)

[Claims] (1) When a predetermined voltage is applied between the drain and the source with a channel width to channel length ratio of at least one of the vacant area on the chip or the scribe line, a drain-source current of 1 μA flows. The threshold voltage is set so that the gate-to-source voltage at the current time is equal to the threshold voltage extrapolated from the gate-to-source voltage and the square root of the drain-to-source current when a predetermined voltage is applied between the drain and source. A MIS type semiconductor integrated circuit device characterized by being provided with a monitor transistor. (2) An N whose gate is connected between the first pad and the second pad and whose gate is connected to the third pad in at least one of the vacant area on the chip or on the scribe line.
A monitor circuit consisting of a channel type MOS transistor and a P channel type MOS transistor connected between a fourth pad and the second pad and having a gate connected to the third pad is provided, and each of the MOS transistors The ratio of channel width to channel length is 1 μA when a predetermined voltage is applied between the drain and source.
Gate-source voltage when source current flows and gate-source voltage when a specified voltage is applied between drain and source.
1. A MIS type semiconductor integrated circuit device, wherein a threshold voltage extrapolated from a source voltage and a square root of a drain-source current is set to be equal.